The Tor Project-The Onion Router

Overview

The Tor Project, Inc. is a 501(c)(3) research-education nonprofit organization founded in 2006 to develop and maintain free, open-source software for anonymous internet communication. It is responsible for the Tor network—a decentralized overlay network run by more than 7,000 volunteer-operated relays worldwide—and the suite of tools built on top of it, including Tor Browser, Tails OS (merged into the Tor Project in September 2024), Snowflake, and onion services. The name "Tor" stands for The Onion Router, a reference to the layered encryption at the heart of the technology. Tor is widely described as the world's strongest publicly available tool for private, censorship-resistant internet access, and is used by millions of people including journalists, human rights defenders, whistleblowers, activists, and ordinary citizens seeking to protect their privacy. Its executive director is Isabela Fernandes. The Tor Project's budget was $7.3 million as of June 2024, of which 35% came from US government sources — down from 80% in 2012 — with Mullvad VPN as the second-largest single contributor at 19%, and a significant and strategically valued portion coming from individual donations.

History and Founding

The intellectual origins of Tor lie not in civil society but in the US military. In 1995, researchers David Goldschlag, Mike Reed, and Paul Syverson at the US Naval Research Laboratory (NRL) began working on a fundamental challenge: how to protect government communications on the internet in a way that concealed not just the content of messages—encryption already handled that — but the routing metadata that revealed who was communicating with whom. Their answer was onion routing: wrapping traffic in multiple layers of encryption and bouncing it through a chain of intermediate servers, such that each server only ever knows the identity of the server before it and the server after it, never the origin and destination simultaneously. The routing information peels away one layer at a time, like an onion.

The NRL team quickly grasped an essential paradox: for onion routing to protect high-risk users, it had to be used by a large crowd of ordinary people. If only intelligence operatives used the system, connecting to it would itself be a signal. In 1997, at the Information Hiding Workshop in Oakland, the NRL researchers met members of the cypherpunk community—privacy activists working on cryptographic tools for mass use — and began collaborating on a design suitable for the public. That meeting, held over vegetarian lasagna and, reportedly, roasted onions, seeded the alliance between government security research and civil-libertarian activism that has defined Tor ever since.

Roger Dingledine began working on an NRL onion routing project with Syverson in the early 2000s. To distinguish it from other onion routing research, he named the project Tor. Nick Mathewson, a classmate of Dingledine's at MIT, joined shortly after. In October 2002, the Tor network was deployed and its code released under a free and open-source licence. By the end of 2003 it had about a dozen volunteer nodes, mostly in the US plus one in Germany. In 2004, the Electronic Frontier Foundation recognized Tor's importance to digital rights and began funding Dingledine's and Mathewson's work. On 22 December 2006, Dingledine, Mathewson, and five others formally incorporated The Tor Project, Inc. as a Massachusetts nonprofit. The EFF served as fiscal sponsor in the early years; early financial supporters also included the US International Broadcasting Bureau, Internews, Human Rights Watch, the University of Cambridge, and Google.

The 2013 Snowden revelations transformed Tor's public profile. Not only had Tor been instrumental to Snowden's whistleblowing communications, but the leaked NSA documents confirmed that, at that time, the agency could not crack it—a rare public validation of Tor's effectiveness from its most formidable adversary. The revelations brought mainstream awareness to mass surveillance and drove a surge in Tor users and volunteers. In 2015, former EFF executive director Shari Steele joined as executive director, professionalizing the organization's operations. The Tor Project has received the Free Software Foundation's Award for Projects of Social Benefit (2011), the EFF Pioneer Award (2012), and recognition from Foreign Policy as among the world's top 100 global thinkers.

Technology and Tools

Tor network. The core infrastructure: a decentralized, volunteer-operated network of more than 7,000 relays and over 2,660 bridges (as of 2023 data). When a user connects, their traffic is routed through three randomly selected relays—an entry (guard) node, a middle node, and an exit node. Each relay decrypts one layer of encryption to learn only the address of the next relay; none can see both the origin and destination. The network is designed such that security scales with diversity: the more independent operators running relays in different countries and jurisdictions, the harder it is for any single adversary to monitor the whole system.

Tor Browser. A hardened, privacy-configured build of Firefox that routes all traffic through the Tor network by default. It blocks tracking scripts, disables browser plugins, prevents fingerprinting, does not retain browsing history, and isolates cookies per site. Available for Windows, macOS, Linux, and Android. Tor Browser is the primary entry point for most Tor users.

Onion services (.onion sites). A feature of the Tor network that allows servers to operate with hidden IP addresses, accessible only via Tor. Onion services provide an additional privacy layer even beyond ordinary Tor browsing: traffic never leaves the Tor network. They are used by major news organizations—including The New York Times, BBC, and The Guardian—to provide censorship-resistant access to their content, as well as by SecureDrop, the widely used secure whistleblower submission platform.

Tails OS. The Amnesic Incognito Live System—a privacy-hardened operating system that boots from a USB drive, routes all traffic through Tor, leaves no trace on the host computer, and amnesically resets at shutdown unless the user explicitly saves data to an encrypted persistent storage. Originally an independent project, Tails approached the Tor Project in late 2023 about merging. The merger completed on 26 September 2024, with Tails developers joining the Tor Project's organizational structure while maintaining their own development focus.

Snowflake. A pluggable transport that disguises Tor traffic as ordinary video or voice call traffic—making it much harder for censors to detect and block. Snowflake relies on volunteers who run browser-based proxies: anyone can install the Snowflake extension and help users in censored regions access Tor, with minimal technical requirements and no visibility into what those users browse. As of 2023, over 130,000 people were running Snowflake proxies. Iran, Russia, and China are the countries with the most Snowflake users.

Mullvad Browser. Announced in April 2023, a collaboration between Tor Browser developers and Mullvad VPN: a privacy-preserving browser offering similar protections to Tor Browser—anti-fingerprinting, no browsing history, aggressive tracker blocking—but using a commercial VPN connection rather than the Tor network, for users who prefer that trade-off. Mullvad became the Tor Project's second-largest single funder as part of this partnership, contributing 19% of the project's 2024 budget.

Access and Usage

Tor Browser and all Tor Project tools are free to download and use at torproject.org. Tails OS can be downloaded at tails.boum.org. The Snowflake browser extension is available for all major browsers. All software is free and open source; the Tor network itself depends on volunteers who run relays and bridges—anyone with a suitable server can contribute. The Tor Project blog at blog.torproject.org publishes security advisories, release announcements, policy commentary, and community news. Tor Project also hosts digital security guides from organizations such as Freedom of the Press Foundation and Tactical Tech at community.torproject.org. The organization accepts donations through its website and via a dedicated Bug Smash Fund, whose contributions — unrestricted by funders—are used specifically to fix software bugs outside the scope of grant funding. The Tor Project supports users facing censorship through its user support team and offers training and outreach programs for journalists, activists, and human rights defenders, frequently in partnership with civil society organizations worldwide.